public class ReferenceCountingGG {
    public Object instance=null;
    private static final int _1MB=1024*1024;
    /**
     * 这个成员属性的唯一意义就是占点内存，以便在GC日志中看清楚是否被回收过
     */
    private byte[] bigSize=new byte[2*_1MB];
    
    public static void main (String[] args) {
        ReferenceCountingGG objA=new ReferenceCountingGG();
        ReferenceCountingGG objB=new ReferenceCountingGG();
        objA.instance=objB;
        objB.instance=objA;
        objA=null;
        objB=null;
    }
}
